* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|-4800|2|29|23|59|59}}</nowiki></tt> returns {{{{BASEPAGENAME}}|-4800|2|29|23|59|59}} (''proleptic'') (in ''year 4801 BC''), last Gregorian date where the result is '''false''' (the returned JD is too large by 365 days)

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* <tt><nowiki>{{JULIANDAY|-4800|2|29|23|59|59}}</nowiki></tt> returns {{JULIANDAY|-4800|2|29|23|59|59}} (''proleptic'') (in ''year 4801 BC''), last Gregorian date where the result is '''false''' (the returned JD is too large by 365 days)

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|0|12|30}}</nowiki></tt> returns {{{{BASEPAGENAME}}|0|12|30}} (''proleptic'') (Julian ''[[Anno Domini]]'', first day in proleptic Julian year 1 AD, or December 30 in proleptic Gregorian year 1 BC)

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* <tt><nowiki>{{JULIANDAY|0|12|30}}</nowiki></tt> returns {{JULIANDAY|0|12|30}} (''proleptic'') (Julian ''[[Anno Domini]]'', first day in proleptic Julian year 1 AD, or December 30 in proleptic Gregorian year 1 BC)

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|200|2|28}}</nowiki></tt> returns {{{{BASEPAGENAME}}|200|2|28}} (''proleptic'') (last day of Julian leap year 200 AD, not leap in the proleptic Gregorian calendar)

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* <tt><nowiki>{{JULIANDAY|200|2|28}}</nowiki></tt> returns {{JULIANDAY|200|2|28}} (''proleptic'') (last day of Julian leap year 200 AD, not leap in the proleptic Gregorian calendar)

−

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|200|3|1}}</nowiki></tt> returns {{{{BASEPAGENAME}}|200|3|1}} (''proleptic'') (first day where the Julian and proleptic Gregorian calendars are '''equivalent''')

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* <tt><nowiki>{{JULIANDAY|200|3|1}}</nowiki></tt> returns {{JULIANDAY|200|3|1}} (''proleptic'') (first day where the Julian and proleptic Gregorian calendars are '''equivalent''')

−

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|300|2|28}}</nowiki></tt> returns {{{{BASEPAGENAME}}|300|2|28}} (''proleptic'') (last day where the Julian and proleptic Gregorian calendars are '''equivalent''')

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* <tt><nowiki>{{JULIANDAY|300|2|28}}</nowiki></tt> returns {{JULIANDAY|300|2|28}} (''proleptic'') (last day where the Julian and proleptic Gregorian calendars are '''equivalent''')

−

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|300|3|1}}</nowiki></tt> returns {{{{BASEPAGENAME}}|300|3|1}} (''proleptic'') (first day of difference between the Julian and proleptic Gregorian calendars, in leap Julian year 300 AD, not leap in the proleptic Gregorian calendar)

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* <tt><nowiki>{{JULIANDAY|300|3|1}}</nowiki></tt> returns {{JULIANDAY|300|3|1}} (''proleptic'') (first day of difference between the Julian and proleptic Gregorian calendars, in leap Julian year 300 AD, not leap in the proleptic Gregorian calendar)

−

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|325|3|21}}</nowiki></tt> returns {{{{BASEPAGENAME}}|325|3|21}} (''proleptic'') (spring equinox observed at the Christian [[First Council of Nicaea]], taken as a reference for aligning the Julian calendar to the proleptic Gregorian)

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* <tt><nowiki>{{JULIANDAY|325|3|21}}</nowiki></tt> returns {{JULIANDAY|325|3|21}} (''proleptic'') (spring equinox observed at the Christian [[First Council of Nicaea]], taken as a reference for aligning the Julian calendar to the proleptic Gregorian)

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|2000|12|31}}</nowiki></tt> returns {{{{BASEPAGENAME}}|2000|12|31}} (last day of the [[2nd millennium]] and of the [[w:20th century|20th century]] in the Gregorian calendar)

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* <tt><nowiki>{{JULIANDAY|2000|12|31}}</nowiki></tt> returns {{JULIANDAY|2000|12|31}} (last day of the [[2nd millennium]] and of the [[w:20th century|20th century]] in the Gregorian calendar)

−

* <tt><nowiki>{{</nowiki>{{BASEPAGENAME}}<nowiki>|2001|1|1}}</nowiki></tt> returns {{{{BASEPAGENAME}}|2001|1|1}} (first day of the [[3rd millennium]] and of the [[w:21st century|21st century]] in the Gregorian calendar)

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* <tt><nowiki>{{JULIANDAY|2001|1|1}}</nowiki></tt> returns {{JULIANDAY|2001|1|1}} (first day of the [[3rd millennium]] and of the [[w:21st century|21st century]] in the Gregorian calendar)

The result is valid for all proleptic Gregorian calendar dates starting on March 1, 4801 BC at midnight.

Syntax:

{{JULIANDAY|year|[month]|[day]|[hour]|[minute]|[second]}}

The year (required) must be astronomical (year=1 in 1 AD (Anno Domini), year=0 in 1 BC, year=-1 in 2 BC).

The month (optional, default value 1) is expressed between 1 and 12 from January to December (but offsets are possible for computing other years).

The year and month are first converted into a number of months, then rounded to the nearest integer to compute the actual year and month used for computing dates.

The day (optional, default value 1) is normally between 1 and 31 (but offsets are possible for computing other months). Decimals are possible for fractions of day.

The hour (optional, default value 12) is normally between 0 and 23 (but offsets are possible for computing other days). Note that Julian days begin at noon (hour = 12) and thus hours 0-11 of a solar day are one Julian day earlier than hours 12-23. The value may extend outside of the normal range and is considered as additional number of julian days (a Julian day is 24 hours or 86400 seconds exactly, ignoring any adjustment of leap seconds within the UTC calendar). Decimals are possible for fractions of hour.

The minute and second (optional, default value 0) are normally between 0 and 59 (but offsets are possible for computing other hours). Decimals are possible for fractions of minute or second.

All parameters can be any valid numeric expression which is evaluated before computing.

Note:

The julian day, when computed modulo 7, grows from 0 (on Monday at noon) to 6 (on Sunday at noon)) and falls back to 0 (on next Monday). This corresponds to the order of days in the ISO week.

Examples:

{{JULIANDAY|-4800|2|29|23|59|59}} returns -32044.500011574 (proleptic) (in year 4801 BC), last Gregorian date where the result is false (the returned JD is too large by 365 days)

{{JULIANDAY|-4800|3|1|0|0|0}} returns -32410.5 (proleptic) (in year 4801 BC), first Gregorian date where the result is correct

{{JULIANDAY|200|2|28}} returns 1794167 (proleptic) (last day of Julian leap year 200 AD, not leap in the proleptic Gregorian calendar)

{{JULIANDAY|200|3|1}} returns 1794168 (proleptic) (first day where the Julian and proleptic Gregorian calendars are equivalent)

{{JULIANDAY|300|2|28}} returns 1830691 (proleptic) (last day where the Julian and proleptic Gregorian calendars are equivalent)

{{JULIANDAY|300|3|1}} returns 1830692 (proleptic) (first day of difference between the Julian and proleptic Gregorian calendars, in leap Julian year 300 AD, not leap in the proleptic Gregorian calendar)

{{JULIANDAY|325|3|21}} returns 1839843 (proleptic) (spring equinox observed at the Christian First Council of Nicaea, taken as a reference for aligning the Julian calendar to the proleptic Gregorian)